In treating toilet flush water with chemicals in order to produce desirable effects such as bowl aesthetics, cleaning, disinfection, deodorization, aerosol reduction, etc., it is desirable that the chemicals be dispensed into the flush water automatically each time the toilet is flushed. The prior art discloses numerous devices which have been designed for this purpose. Exemplary of such devices are disclosed in:
U.S. Pat. No. 4,171,546, Dirksing, issued Oct. 23, 1979; PA1 U.S. Pat. No. 4,186,856, Dirksing, issued Feb. 5, 1980; PA1 U.S. Pat. No. 4,200,606, Kitko, issued Apr. 29, 1980; PA1 U.S. Pat. No. 4,208,747, Dirksing, issued June 24, 1980; PA1 U.S. Pat. No. 4,216,027, Wages, issued Aug. 5, 1980; PA1 U.S. Pat. No. 4,246,129, Kacher, issued Jan. 20, 1981; PA1 U.S. Pat. No. 4,247,070, Dirksing, issued Jan. 27, 1981; PA1 U.S. Pat. No. 4,248,827, Kitko, issued Feb. 3, 1981; PA1 U.S. Pat. No. 4,251,012, Williams et al., issued Feb. 17, 1981; PA1 U.S. Pat. No. 4,253,951, McCune, issued Mar. 3, 1981; PA1 U.S. Pat. No. 4,281,421, Nyquist et al., issued Aug. 4, 1981; PA1 U.S. Pat. No. 4,283,300, Kurtz, issued Aug. 11, 1981; PA1 U.S. Pat. No. 4,302,350, Callicott, issued Nov. 24, 1981; PA1 U.S. Ser. No. 355,984, Mueller et al., filed Mar. 8, 1982; and European Pat. Appln. 0,005,286, Nyquist, published Nov. 14, 1979, all of which are incorporated herein by reference. PA1 1. Charge a Crutcher mixer equipped with agitation and recirculation with an alkali metal alkyl sulfate (e.g., sodium lauryl sulfate). PA1 2. Add more or less of a stoichiometric amount of magnesium sulfate with agitation and recirculation. PA1 3. Mix and recirculate. PA1 4. Add a sufficient amount of a buffer salt, preferably sodium carbonate, to insure that the pH of the reaction solution is 6 to 10, preferably 7 to 9.5. PA1 5. Mix and recirculate for about 30 minutes. PA1 6. Pump the buffered solution to a storage tank (optional). PA1 7. Pump the buffered reaction product solution onto drum roll dryers having a temperature of from about 120.degree. C. to about 140.degree. C. Drying conditions should maintain the pH of 6 to 10. PA1 8. If fatty alcohol is to be added, determine how much is in the dried product of Step 7. PA1 9. Agglomerate in an amalgamator the dried flakes of Step 7 along with other ingredients such as extra filler salt, perfume, dyes, free fatty alcohol etc. Amalgamate. PA1 10. Plod the amalgamated mixture of Step 8 and then extrude into strips. PA1 11. Cut into cakes. PA1 12. Place the cakes into dosing dispensers and seal.
Particularly desirable devices are those comprising a solid cake composition. In this type of device a measured amount of water enters the device during one flush cycle and remains in contact with the cake between flushes, thereby forming a concentrated solution of the composition which is dispensed into the flush water during the next flush. The advantages of such devices are that the chemical composition can be packaged and shipped in more concentrated form than aqueous solutions of the chemicals. Also, the problems of liquid spillage resulting from breakage of the dispensers during shipment or handling is eliminated. Especially preferred devices for automatic dispensing of chemicals from solid cake compositions into the toilet are those described in U.S. Pat. No. 4,171,546, Dirksing, issued Oct. 23, 1979; U.S. Pat. No. 4,208,747, Dirksing, issued June 24, 1980; U.S. Pat. No. 4,186,856, Dirksing, issued Feb. 5, 1980; all of which are incorporated by reference. A preferred version of the dispenser is used in BRIGADE.sup.R, an automatic toilet bowl cleaner sold by The Procter & Gamble Company.
Prior art surfactant cake compositions used in the "Dirksing" dispensing devices are disclosed in U.S. Pat. No. 4,308,625, Kitko, issued Jan. 5, 1982; U.S. Pat. No. 4,310,434, Choy and Greene, issued Jan. 12, 1982; and U.S. Pat. No. 4,278,5671, Choy, issued July 14, 1981, entitled "Surfactant Cake Compositions;" all of which are incorporated herein by reference. The surfactants provide cleaning and sudsing in the toilet bowl and also serve to dispense other components of the compositions such as dyes, perfumes, organic resins, etc. Anionic surfactants, especially the organic sulfates and sulfonate types, are used in these compositions because of their availability, low cost and excellent cleaning and dispensing properties.
Water-soluble inert salts such as alkali metal chlorides and sulfates are used in such compositions to act as a "filler" so that the composition can be formed into cakes of desirable size without using excessive amounts of active ingredients. The predominant ingredients of the cake compositions are usually the surfactant, perfume and the filler salt. Anionic, nonionic, ampholytic, zwitterionic or cationic surfactants are used. The surfactant or surfactant mixture should be solid at temperatures up to about 100.degree. F. (40.degree. C.). Anionics and nonionics and mixtures thereof are useful. Anionics are the most preferred.
The prior art anionic surfactant cakes can be described as essentially the water-soluble alkali metal salts, of organic sulfuric reaction products having in their molecular structure an alkyl or an alkylaryl radical containing from 8 to 22 carbon atoms.
A major problem in this art has been short and/or erratic longevity of surfactant cakes. "Hot spots," for example, cause rapid and uneven dissolution and decreased cake stability and longevity. A hot spot is localized decomposition of the surfactant and is characterized by a pH of 1 or 2 and a high concentration of free fatty alcohol. Another problem is related to the incorporation of higher levels of perfume into surfactant cake formulations while maintaining desired firmness.